Rosserial nodes not starting after last update

I just ran a ROS package update on my Ubuntu 16.04 system, and now none of my rosserial serial_node.py instances are starting. My launch file is like: but running this now results in: [rospy.client][INFO] '2018-05-30 23:43:20': init_node, name[/torso_arduino/serial_node], pid[1195] [xmlrpc][INFO] '2018-05-30 23:43:20': XML-RPC server binding to 0.0.0.0:0 [xmlrpc][INFO] '2018-05-30 23:43:20': Started XML-RPC server [http://robot:33755/] [rospy.impl.masterslave][INFO] '2018-05-30 23:43:20': _ready: http://robot:33755/ [xmlrpc][INFO] '2018-05-30 23:43:20': xml rpc node: starting XML-RPC server [rospy.registration][INFO] '2018-05-30 23:43:20': Registering with master node http://localhost:11311 [rospy.init][INFO] '2018-05-30 23:43:20': ROS Slave URI: [http://robot:33755/] [rospy.init][INFO] '2018-05-30 23:43:20': registered with master [rospy.rosout][INFO] '2018-05-30 23:43:20': initializing /rosout core topic [rospy.rosout][INFO] '2018-05-30 23:43:20': connected to core topic /rosout [rospy.simtime][INFO] '2018-05-30 23:43:20': /use_sim_time is not set, will not subscribe to simulated time [/clock] topic [rosout][INFO] '2018-05-30 23:43:20': ROS Serial Python Node [rospy.internal][INFO] '2018-05-30 23:43:20': topic[/rosout] adding connection to [/rosout], count 0 [rosout][INFO] '2018-05-30 23:43:20': Connecting to /dev/ttyACM0 at 115200 baud [rospy.core][INFO] '2018-05-30 23:43:20': signal_shutdown [atexit] [rospy.internal][INFO] '2018-05-30 23:43:20': topic[/rosout] removing connection to /rosout [rospy.impl.masterslave][INFO] '2018-05-30 23:43:20': atexit How do I read this? It's not producing any error log messages, but it seems to be saying it's getting a signal to exit, but it's unclear where. What's changed and how do I fix this? Is it normal for such a massive backward-compatible change been made to an LTS release?